Add weighted version of eigenvector centrality

[qiemem]

Requested by user.

This shouldn't be too hard to implement. This paper by Newman states that adding weights doesn't change anything: you still just use an eigenvector of the largest eigenvalue of the adjacency matrix. Thus, we should just be able to add in weight as factor in this line: https://github.com/NetLogo/NW-Extension/blob/hexy/src/main/org/nlogo/extensions/nw/algorithms/CentralityMeasurer.scala#L22